Imaging caries lesions and lesion progression with polarization-sensitive optical coherence tomography

Abstract

New diagnostic tools are needed for the characterization of dental caries in the early stages of development. If carious lesions are detected early enough, they can be arrested without the need for surgical intervention. The objective of this study was to demonstrate that polarization sensitive optical coherence tomography (PS-OCT) can be used for the imaging of early caries lesions and for the monitoring of lesion progression over time. High-resolution polarization resolved images were acquired of natural caries lesions and simulated caries lesions of varying severity created over time periods of 1 to 14 days. Linearly polarized light was incident on the tooth samples and the reflected intensity in both orthogonal polarizations was measured. PS-OCT was invaluable for removing the confounding influence of surface reflections and native birefringence and for resolving the surface structure of caries lesions. This study demonstrated that PS-OCT is well suited for the resolution of interproximal and occlusal caries, early root caries, and secondary caries around composite fillings. Longitudinal measurements of lesion progression established a strong correlation (p<0.001) between the reflected light from the lesion area and the square root of time indicating that PS-OCT is well suited for monitoring changes in enamel mineralization over time.

Evaluation of two quantitative analysis methods of optical coherence tomography for detection of enamel demineralization and comparison with microhardness

“…Near‐infrared OCTs are generally used for biological tissues because light in that spectral region undergoes minimal absorption and moderate scattering, allowing imaging with micrometric resolution to a depth of 3 mm, typically . The OCT technique has been successfully applied to the diagnosis of dental caries due to changes in the optical properties of enamel after undergoing demineralization . Images obtained by OCT can be evaluated qualitatively by identification of structures, dimensions, and proportions , and quantitatively, for example by analyzing the reflectivity or the total optical attenuation .…”

“…The OCT technique has been successfully applied to the diagnosis of dental caries due to changes in the optical properties of enamel after undergoing demineralization . Images obtained by OCT can be evaluated qualitatively by identification of structures, dimensions, and proportions , and quantitatively, for example by analyzing the reflectivity or the total optical attenuation . Using OCT, it has been demonstrated in several studies that demineralized enamel shows stronger optical backscattering , and different authors have extensively studied the characteristics and the dynamic of the remineralization of enamel, for teeth submitted to different periods of pH cycling .…”

A method for monitoring enamel erosion using laser irradiated surfaces and optical coherence tomography

“…The PS‐OCT system is completely controlled using Labview software (National Instruments, Austin, TX). The system is described in greater detail . Acquired scans are compiled into b‐scan files.…”

“…Previous studies have shown that polarization sensitive optical coherence tomography (PS‐OCT) can nondestructively measure the severity of subsurface demineralization in enamel and dentin and is therefore well suited for this role . Early in vitro studies of the use of OCT for monitoring tooth demineralization demonstrated that OCT can be used to measure the loss of enamel due to exposure to a demineralizing solution.…”

“…Early in vitro studies of the use of OCT for monitoring tooth demineralization demonstrated that OCT can be used to measure the loss of enamel due to exposure to a demineralizing solution. In the study of Fried et al , acid resistant varnish was added to a control surface and this surface served as a reference surface to quantify the loss of enamel exposed to erosion. Although this approach is simple to implement in vitro , more robust adhesives such as composites would be needed in order to employ it in vivo and they would have to be employed in areas that are not subject to wear.…”